Transparency artifacts android

When testing my project on a Samsung S5 mini, I noticed artifacts around the edges. At first I thought it was because of mipmapping but as you can see in the screenshot, the details on the texture are in fact in high resolution. The edges should look like this: Which it does on a Samsung S6 and on PC. When I encountered a similar artifact before it seemed lik it got worse over time but I'm not sure if it's also the case with this problem.

Does someone know what might cause this problem? Is it the lack of memory of the S5? The texture size is about 4k by 4k and the background texture is 1080p.

The shader decreases the opacity based on the distance to the camera, it starts at a distance of 5 units and takes about 1 unit to become completely invisible.